1. Field of the Invention
This invention relates generally to rolling mills producing continuously hot rolled steel bars, rods and the like, and is concerned in particular with an improvement which enables existing mills to benefit from the cost savings associated with rolling larger billets, without necessitating either a relocation or a substantial reconfiguration of the billet reheating furnace.
2. Description of the Prior Art
Rod producers are now facing increasing demands for larger heavier rod coils and/or improved metallurgical properties throughout the entire cross section of the rod. Rolling longer billets will satisfy the first demand, but not the second. Rolling standard length billets with larger cross sections satisfies both demands.
The resulting coils are larger and heavier, and the higher total reductions required to roll the larger billets down to rod sized will impart improved metallurgical properties uniformly from the surface to the center of the rods.
In the conventional rolling mill installation, the entry end of the roughing section is positioned in close proximity to the exit door of the billet reheating furnace. This allows rolling to commence as soon as the billet emerges from the furnace, with minimum heat loss. However, should the mill operator wish to decrease the cross section of the billet being rolled, there is insufficient space available on the rolling line to accommodate the additional roll stands needed to roll the larger cross sections down to sizes suitable for continued rolling in the remainder of the existing mill.
Space can be freed up by moving or substantially reconfiguring the furnace, or by rearranging equipment along the rolling line. However, the costs involved in doing so, both with regard to capital expenditures and lost production time, are extremely high and in most cases, prohibitive.
The objective of the present invention is to provide an apparatus layout and a method of rolling which enables larger billets to be rolled through an existing mill, without having to substantially reconfigure or move the billet reheating furnace, and with only a minimum loss of valuable production time.